1. Field of the Invention
This invention relates to apparatuses and methods for diagnosing and/or treating tissues/cells using electromagnetic fields, and for determining therapeutically useful electromagnetic fields, and harmful electromagnetic fields.
2. The State of the Art
Electromagnetic fields are used clinically for bone and wound healing and have been used experimentally to enhance nerve repair and/or regeneration. Most investigators have varied a very limited number of electric parameters, usually to show that the biological effect does exist, but without an attempt to optimize this effect. In contrast, the present invention undertakes a systematic approach to evaluate different signals and their components in a complex neuron explant model as a first step toward verification of the in vivo efficacy of such defined EM fields.
There are approximately 500,000 cases of nerve injury of upper extremities per year. Recovery from pain and restoration of function is slow and there is a need for more research in this area to speed up the whole process (Sisken and Walker, 1995).
The EMF signals which have been tested most extensively both in vitro and in vivo are 15 Hz pulse train as well as 72 Hz repetitive single pulse (EBI, Inc., Parsippany, N.J.) and 2 Hz repetitive single pulse (Bietic Research, Inc., Lyndhurst, N.J.) measured as a voltage induced in a small pick-up coil. A 2 Hz/3 Gauss field signal was tested in vivo, resulting in an increased axon elongation (Sisken et al, 1989) in the crushed rat sciatic nerve; the regeneration rate was enhanced by 22%, which is comparable to that reported in the literature with conditioning lesions, growth factors and hormones (Sisken et al, 1993).
In vitro results using 2 Hz/0.5 Gauss EMF on the cultured dorsal root ganglia (DRG) explants showed significantly increased neurite outgrowth (Sisken et al, 1990). DRG explants in culture are a well-established in vitro model to study effects of different factors on nerve regeneration (Greenebaum et al, 1994). The chick DRG has been used as a model testing system for growth factor effects and mechanisms for the past 40 years (Levi-Montalcini, 1968). The dorsal root ganglion is the sensory part of the sensory-motor axis; sensory neurons are in the ganglia whereas motor neurons are in the ventral portion of the spinal cord.
The equipment used most often for in vitro and in vivo studies of low frequency electromagnetic field effects on nerve regeneration was developed originally for bone healing (Electro-Biology, Inc., Parsippany, N.J.) and delivers either a repetitive 72 Hz single pulse or a pulse train with a repetition rate of 15 Hz. Nerve regeneration studies using this equipment were performed by: Ito and Bassett; Orgel et al; and Subramanian et al. The RF signal Diapulse system has also been used for nerve regeneration experiments (Wilson; Raji and Bowden). Some investigators (Blackman; Rusovan et al; Subramanian et al) used various sinusoidal EMFs. A repetitive single pulse system by Bietic Research, Inc. (Lyndhurst, N.J.) has also been used in wound healing and nerve regeneration experiments (Sisken et al; Orgel et al). For review of the above studies, see Sisken (1991).